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 SOLVED Interesting by-the-book repair

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copain



Join date : 2011-12-28

PostSubject: SOLVED Interesting by-the-book repair   2012-07-10, 2:55 pm

The RCA model 56X5 is a well-known and great performing six-tube AC-DC receiver. I acquired one years ago and use it frequently. However, yesterday it presented a nasty problem, although a problem that I knew was covered in Marcus and Levy's Practical Radio Servicing, the best darned text for servicing AC-DC receivers ever written, and if you don't have a copy, do whatever it takes to acquire one. This book is especially invaluable to beginners. The problem: After the radio had played about three minutes, the dial lamp would flicker, then almost go out, then return to full brightness, then flicker again, and, finally, go out completely, shutting down the radio. After this problem recurred three or four times I remembered reading about in Practical Radio Servicing. Using the index, I found the pages where this very problem is treated. It is caused by a tube with an intermittently bad heater. Marcus and Levy have a procedure for finding which tube is the troublemaker, stating that usually it is either the rectifier or the second audio tube. Naturally, I first tried replacing each of these. Unfortunately, the problem remained. I then deluded myself into thinking that a poor connection was at fault and started probing components and connections, but, again, to no avail. A little voice in my head, which I should have listened to promptly, kept telling me that there are four other tubes and any of them could be responsible. The next two that I tried by direct substitution did not solve the problem, but the third one I tried did, as attested by the fact that the receiver ran almost four hours on the bench without the problem recurring. The bad tube, incidentally, was a 12SK7; it has a new home now: the bottom of my shop trash barrel.

One very nice feature of the 56X5 is that it has spread bands for the crowded 25 and 31 meter bands.
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Cliff Jones
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Join date : 2010-11-22

PostSubject: Re: SOLVED Interesting by-the-book repair   2012-07-11, 11:13 pm

Good to know it worked out Very Happy
Leave no stone uncovered is the best.
Worth knowing what you found out. cheers
Added Solved to your Post Basketball

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Cliff Jones
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PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-14, 12:42 pm

Another book by Markus Marcus and Levy is called Profitable Radio Troubleshooting and is very detailed in finding and locating pesky faults. I am currently reading it and cannot put it down. I am at page 92 and finding this is one of the best books in my Library.

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Last edited by Cliff Jones on 2013-06-14, 2:29 pm; edited 1 time in total
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copain



Join date : 2011-12-28

PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-14, 1:16 pm

Yes, I also have this book.  It is the least known of the M&L books, and is especially noteworthy for its troubleshooting charts. Its material on pricing your work and dealing with customers is, of course, pretty passe.   By the way, note that the correct spelling  is Marcus, with a letter c, not a k as you show it.  I mention this because there is a veritable Markus who has another pretty good radio (and TV) book, Television and Radio Servicing (1953, rev. 1961).  It is full of valuable servicing information aimed at newcomers, such as high school kids in the long-gone days when this kind of vocational education was  available and kids did not have to go to school under armed guard.
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Cliff Jones
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PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-14, 2:09 pm

scratch           Hmm! Yep! I stand corrected. EmbarassedVery Happy

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Cliff Jones
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PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-14, 2:22 pm

Now I am going to get my Old URM 25D (just purchased 2 weeks ago) and use it per that book,  to make things easier. Now I will have to become familiar with that Generator and set up.

By golly I just found another one of their M&L books called Elements of Radio Servicing in my Library. Looks to be very similar. Shocked

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copain



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PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-19, 2:02 pm

Elements of Radio Servicing has  been mentioned a lot in this forum.  It is available also as a free download via a link in the Antique Radio Forums site.  It is "similar" to the same authors' Profitable Radio Troubleshooting only insofar as both books treat the repair of tube radios.  Elements deals almost exclusively with AC-only radios and presents a troubleshooting routine that makes use of a signal generator.  It was planned to be understandable by high school vocational students and, thus, is very "textbookish"--as it should be.  Both authors knew how to write and how to make themselves clear and worked closely with experienced textbook editors in producing outstanding learning material.   Incidentally, an item sold by the publisher as an optional extra is extremely rare; I've never seen it: a set of 35 mm filmstrips designed for classroom use.
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Cliff Jones
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PostSubject: Re: SOLVED Interesting by-the-book repair   2013-06-19, 4:22 pm

At the back of my mind there was a Troubleshooting chart that was loose-leaf with one of the books but is very rare to find it now.

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